1) The oven needs to be preheated 220 Degree Fahrenheit.
2) A baking tray must be lined using non-stick balking paper.
3) One pastry sheet should be cut into 8 strips.
4) The remaining pastry sheet needs to be placed on the tray.
5) For creating a border, 2 pastry strips have to be placed on top of each other along the edge of the sheet.
6) The excess pastry needs to be trimmed at the corners.
7) The pastry edges should be pinched to decorate.
8) One egg and sour cream should be whisked in a bowl and make sure that they are well combined.
9) Salt and pepper must be used to season.
10) The Swiss cheese and cheddar cheese must be stirred in.
11) The cheese mixture needs to be spread over the pastry and 2-cm border should be left around the edge.
12) The ham has to be arranged over the cheese mixture in a diamond shape.
13) One tomato half should be placed in the center of each diamond cut-side up.
14) Feta needs to be used to top.
15) The remaining egg must be whisked in a bowl.
16) The pastry edges have to be brushed with the egg.
17) It must be baked for 20 minutes and stop when it turns golden brown.
18) The lemon thyme can be used to top.